This invention relates to heat exchangers for catalytic gas converters, also referred to as reformed-gas generators, in general and more particularly to an improved heat exchanger for such use.
Catalytic gas converters are used for example, in the operation of internal-combustion engines. In such devices, a mixture of fuel and primary air or exhaust gas is catalytically converted into a fuel gas, also referred to as a reformed gas, which is then fed along with secondary air to the internal combustion engine where it is burned. The principle and operation of such devices are disclosed in detail in U.S. patent application Ser. Nos. 218,696 and 270,923 filed respectively on Jan. 18, 1972 and July 12, 1972, both of which are assigned to the same assignee as the present invention.
For proper operation of an internal-combustion engine using a gas converter of this nature, a heat exchanger to cool the fuel gas which is generated in the catalytic gas converter is required. Otherwise, self-ignition of the fuel gas when the secondary air was added thereto, can result with knocking in the internal-combustion engine. Cooling of the reformed gas avoids knocking and at the same time increases the output of the engine by increasing the volumetric efficiency of the cylinders. Furthermore, by using such a heat exchanger, the heat removed from the fuel gas can be utilized for evaporating the fuel supplied to the catalytic gas converter. Also, heat exchangers of the nature disclosed herein, can be used for the heating of the primary air which is fed to the gas converter through the use of the waste heat of the fuel gas or the exhaust gases of the engine.
The heat exchangers used in such catalytic gas converters, which operate at extremely high temperatures, must be gas tight though the gases are aggressive and must be capable of withstanding the high temperature and in addition, must be free of stress so as to be able to withstand frequent temperature changes of large magnitude. In addition, such a heat exchanger must have adequate stability.